//===================================================================================
// Microsoft patterns & practices
// Composite Application Guidance for Windows Presentation Foundation and Silverlight
//===================================================================================
// Copyright (c) Microsoft Corporation.  All rights reserved.
// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE.
//===================================================================================
// The example companies, organizations, products, domain names,
// e-mail addresses, logos, people, places, and events depicted
// herein are fictitious.  No association with any real company,
// organization, product, domain name, email address, logo, person,
// places, or events is intended or should be inferred.
//===================================================================================
using System;
using Microsoft.Practices.Prism.Properties;

namespace Microsoft.Practices.Prism.Regions
{
	/// <summary>
	/// Provides a base class for region's behaviors.
	/// </summary>
	public abstract class RegionBehavior : IRegionBehavior
	{
		private IRegion region;

		/// <summary>
		/// Behavior's attached region.
		/// </summary>
		public IRegion Region
		{
			get
			{
				return region;
			}
			set
			{
				if (this.IsAttached)
				{
					throw new InvalidOperationException(Resources.RegionBehaviorRegionCannotBeSetAfterAttach);
				}

				this.region = value;
			}
		}

		/// <summary>
		/// Returns <see langword="true"/> if the behavior is attached to a region, <see langword="false"/> otherwise.
		/// </summary>
		public bool IsAttached { get; private set; }

		/// <summary>
		/// Attaches the behavior to the region.
		/// </summary>
		public void Attach()
		{
			if (this.region == null)
			{
				throw new InvalidOperationException(Resources.RegionBehaviorAttachCannotBeCallWithNullRegion);
			}

			IsAttached = true;
			OnAttach();
		}

		/// <summary>
		/// Override this method to perform the logic after the behavior has been attached.
		/// </summary>
		protected abstract void OnAttach();
	}
}